Find out a good notion of rectifiability in subRiemannian Carnot groups [1]}, [2]}, [3]} is unanswered questions which have continued to perplex many mathematicians for decades. Starting from a negative result by Ambrosio and Kirchheim [4]}, Franchi, Serapioni and Serra Cassano introduced the notion of intrinsically Lipschitz maps in [5]}, [6]}, [7]} (see also [8]}, [9]}) in order to answer this question. Recently, Le Donne and the author [10]} generalize this concept in metric spaces and prove some relevant properties like Ahlfors-David regularity, Ascoli-Arzelá Theorem, Extension theorem, etc. for the so-called intrinsically Lipschitz sections.
